8 3 DNA Replication KEY CONCEPT DNA replication

8. 3 DNA Replication KEY CONCEPT DNA replication copies the genetic information of a cell.

8. 3 DNA Replication copies the genetic information. • A single strand of DNA serves as a template for a new strand. • The rules of base pairing direct replication. • DNA is replicated during the S (synthesis) stage of the cell cycle. • Each body cell gets a complete set of identical DNA.

8. 3 DNA Replication • Helicase: unzip the DNA and separate the nucleotides of the two strands • DNA polymerase: • Ligase: bond together the nucleotides after the replication

8. 3 DNA Replication Proteins carry out the process of replication. • DNA serves only as a template. • Enzymes and other proteins do the actual work of replication. – Helicase unwind and unzip the double helix.

8. 3 DNA Replication Unwind

8. 3 DNA Replication Unzip

8. 3 DNA Replication DNA unwinding and unzipping process

8. 3 DNA Replication Proteins carry out the process of replication. • Free-floating nucleotides form hydrogen bonds with the template strand. nucleotide The DNA molecule unzips in both directions.

8. 3 DNA Replication – DNA polymerase enzymes bond the nucleotides together to form the double helix. – Polymerase enzymes (ligase) form covalent bonds between nucleotides in the new strand nucleotide DNA polymerase

8. 3 DNA Replication Leading and lagging strands • Leading strand: it is going to replicate continously • Lagging strand: it is going to replicate by patches.

8. 3 DNA Replication • Two new molecules of DNA are formed, each with an original strand a newly formed strand. • DNA replication is semiconservative. original strand Two molecules of DNA new strand

8. 3 DNA Replication is fast and accurate. • DNA replication starts at many points in eukaryotic chromosomes. There are many origins of replication in eukaryotic chromosomes. • DNA polymerases can find and correct errors.